<TITLE>Protocol Specifications relevant to HyperText</TITLE>
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<H1>Relevant protocols</H1>The <A NAME=0 HREF=../TheProject.html>WorldWideWeb</A> system can pick up information from many information
sources, using existing protocols. Among these are file and news transfer
protocols.
<H2><A NAME=11>File Transfer</A></H2>The file transfer protocol currently most used for accessing fairly
stable public information over a wide area is "Anonymous FTP". This
means the use of the internet File Transfer Protocol without authentication.
As the WWW project currently operates for the sake of public information,
anonymous FTP is quite appropriate, and WWW can pick up any information
provided by anonymous FTP. FTP is defined in<A NAME=1 HREF=rfc959.txt> RFC 959</A> which includes
material from many previous RFCs. (See also: <A NAME=2 HREF=../Addressing/FileAddressing.html> file address syntax</A>
). Directories are browsed as hypertext.  The browser will notice
references to files which are in fact accessible as locally mounted
(or on DECnet on VMS systems) and use direct access instead.<P>
See also the prospero project and the <A NAME=10 HREF=../../../Shift/shift0-4.dvi>shift</A> project, for more powerful
file access systems.
<H2>Network News</H2>The "Network News Transfer Protocol" (NNTP) is defined in<A NAME=3 HREF=rfc977.txt> RFC 977</A>
by Kantor and Lampsley. This allows transient news information in
the USENET news format to be exchanged over the internet. The format
of news articles is defined in<A NAME=4 HREF=rfc850.txt> RFC 850, Standard for Interchange of
USENET Messages</A> by Mark Horton. This in turn refers to the standard<A NAME=5 HREF=rfc822.txt>
RFC 822</A> which defines the format of internet mail messages. News articles
make good examples of hypertext, as articles contain references to
other articles and news groups. News groups appear like directories,
but more informative.
<H2>Search and Retrieve</H2>The WWW project defines its own protocol for information transfer,
called HTTP, for <A NAME=9 HREF=HTTP/AsImplemented.html>HyperText Transfer Protocol</A>. HTTP is a very simple
internet protocol, similar in implementation to FTP and NNTP.  The
HTTP client sends a <A NAME=17 HREF=../Addressing/Addressing.html>document identifier</A> with or without search words,
and the server responds with hypertext or plain text. Extensions are
foreseen to allow for more elaborate queries and <A NAME=16 HREF=../DesignIssues/Formats.html#4>format negotiation</A>.
The protocol runs over TCP, using one connection per document request.
The browser acts as a pipeline, so that as data arrives from the server,
it is presented to the reader on the fly.<P>
Whilst the <A NAME=12 HREF=HTTP.html>HTTP</A> protocol provides a simple keyword search function,
a famous search-and-retrieve protocol is Z39.50, and the version of
it used by the <A NAME=13 HREF=../../Products/WAIS/Overview.html>WAIS</A> project.  (See also the WAIS-WWW <A NAME=14 HREF=../Daemon/WAISGate.html>gateway</A>).
<H2>Gopher</H2>The Gopher distributed information system uses a lightweight <A NAME=15 HREF=../../Gopher/gopher_protocol/protocol.rtf>protocol</A>
very similar to HTTP. Therefore, it is now included in every WWW client,
so that the Gopher world can be browsed as part of the Web. Gopher
menus are easily mapped onto hypertext links. Chances are that future
versions of the Gopher and HTTP protocols will converge.